Supervisory signal system



Feb. 27, 1945. A. l.. BROWN SUPERVISORY SIGNAL SYSTEM Filed oct. 31,1942 2 sheets-sheet 1 Y V vA'I'I'ORNEY 'Jew Rishi.

l SMQ UR ms mlb-M- Patented Feb. 27, 1945 2,310,445 sUrERvrsonr SIGNALSYSTEM Andrew L. Brown, Brooklyn, N. Y., assigner to Radio Corporationof America, a corporation of Delaware Application October 31, 1942,Serial No. 464,019

. 6 Claims.. (C1. 178-3) This invention relates to supervisory signalsystems and more particularly to a service signaling arrangement for usein connection with commercial telegraph systems.

Devices for transmitting auxiliary signals independently of the traiiicsignals are well known in the art. It is conventional to use aperforated tape transmitter for trailic signals and to use an auxiliarykeying device for actuating a bell signal, for example. An auxiliarykeying device of that type is disclosed in United States Patent No.2,238,136, granted April 15, 1941, to James A. Spencer.

According to the disclosure of the Spencer patent, it was possible totransmit automatically a succession of signals which comprised caseshift and bell ringing signals for producing any number of bell strokes,say from one to ve. In this manner, the different service signals couldbe transmitted at any time when it was necessary to interrupt theoperation of the tape transmitter.

It has been the usual practice heretofore to transmit the same signalfor bell ringing as for the letter "S or J. In order to differentiatebetween the two functions of the same signal, it was necessary wheneverthe bell signal was to be transmitted to precede the same by a gureshift signal and to follow the bell signal by a letter shift signal.

The transmission of a signal for each bell stroke thus required,according to the prior art, the transmission of three code signals.These three code signals had to be repeated for each stroke of the bell.It is, accordingly, one of the principal objects of my invention toprovide an improved service signal device wherein the bell signal may betransmitted and received without resorting to the use of case shiftsignals.

It is another object of my invention to provide a circuit arrangementwhich incorporates facilities for transmitting service signals, inaddition to an idle-time keyer and a tape stop device operable inresponse to the take-up of slack in the tape by the tape transmitter.

It is still another object of my invention to provide receiving meansselectively responsive to a service signal and independent of otherfacilities for control by ordinary traflic signals.

A feature of my invention resides in its adaptation for the efficienttransmission of bell signais. and its adaptation for conditioning thetransmitter to send an idle-time signal whenever the tape transmitter isstopped longer than to detect the mutilation of a bell signal at thereceiving station.

One of the dimculties which have been encountered in the past is thatthe use of case shift signals in combination with the bell signalsoccasionally resulted in the failure of the receiving printer toproperly transcribe code characters following the transmission of thebell signal. This difficulty was encountered because the auxiliaryservice signaling device might "break in on the tape transmitter in themidst of transmission of upper case characters. The restoration of theprinter unit to lower case characters was automatically performed as thelast function in the automatic bell transmitting unit. Consequently,when the tape transmitter resumed its transmission, the receivingprinter would be left in the lower case position and would thereby printincorrectly the characters which were intended to be in the upper caseand until the tape transmission called for a letter shift signal.

Accordingly, it is an object of my invention to remedy the deficiencyset forth in the preceding paragraph by utilizing a certain combinationof code elements solely for the supervisory bell signal. By eliminatingthe need for the case shift signals preceding and following the bellsignal, the auxiliary signal transmitter may be considerably simplifiedin design.

My invention will now be described in more detail, reference being madeto the accompanying drawings, in which:

Fig. 1 shows a schematic circuit diagram in'- cluding an auxiliaryrservice signal transmitter, an idle-time keying relay, -a tape-slackcontrol device, and other apparatus units which are conventionally usedat a transmitting station; and

Fig. 2 shows a circuit diagram appropriate for use in connection withapparatus units to be operated at a receiving station.

The transmitting apparatus Referring first to Fig. 1, I show therein anarrangement of signaling code composing switches comprised in a unit I0and having seven selective circuits l to 1 inclusive which correspondwith the seven code elements of a now wellknown seven-unit signalingcode. The transmitter keying elements are arranged as contact tongues 8which are positionable in contact with positive contacts 9 or withnegative contacts Il, depending upon whether or not a perforation inmomentarily. The invention is further adapted the tape l2 is sensed byan appropriate seekerpin 1I. For the sake of simplicity in the drawings,the mechanical association of the tongues 8 with the seeker-pins 1I. ismerely indicated by an interconnecting dot-,and-dash line.

During the transmission of a message, the perforated tape I2 is fed at acyclic rate and the perforations therein are sensed cyclically.Different code combinations are thus set up on the tape-controlledtongues 8 for transmission of marking or spacing signaling elements ineach of the seven positions of a uniform length code signal. The codesignals thus formed are normally applied to different segments on amultiplex distributor. Such a distributor is indicated as having a codeelement ring RI and a collector ring R3, the latter being connected tothe outgoing line.

Merely by way of illustration, the transmitting distributor having ringsRI and R3 is shown in Fig. 1 as arranged for a two-channel multiplexsystem. If the system were intended for three or more channels, then thenumber of segments in the distributor ring RI would be proportionatelyincreased, and would be preferably a multiple of seven segments.

In addition to the signal transmitting rings of the distributor, it isconventional to provide a segmented local ring R2 and an energy feederring R4 associated therewith. whereby the cyclic operation of variousmechanisms at the transmitting station may be properly timed. The use ofthe distributor rings R2 and R4 will be hereinafter described inmoredetail.

The brush I8 is used to bridge rings RI and R3 while brush 20 islikewise used to bridge rings R2 and R4. These brushes are insulated onefrom the other, but are mounted for synchronous rotation, beingpreferably driven by a synchronous motor which-is held in step withother portions of the multiplex telegraph system, in accordance with anyof the usual methods of synchronization.

There are two main functionsto be performed by the auxiliary signalingdevices herein shown. One of these is to transmit idle-time signals, andthe other relates to the transmission of service signals such as areusually responded to at the receiving station by a predetermined numberof bell strokes, for example.

The idle-time keying device comprises a relay I6 having three groups ofdouble-throw switches, the tongues of which are referenced A2, A5, andA1. They relate to the transfer of three code element circuits from thetape transmitter Ill to a set of front contacts which are alwayssupplied with positive potential.

'Ihe automatic bell signal keying device comprises a cam-operated switchhaving a follower arm 24 and idler roller 25 which rides over theperiphery of a cam CI. The follower arm 24 actuates certain switchtongues BI, B4, and B1 which have front and back contacts associatedtherewith. The tongue A2 of relay I8 is connected to the back contactassociated with tongue B2 in the bell-signal keying switch. Likewise,the tongue A1 in relay I8 is connected to back contact associated withtongue B1 inthe bell-signal keying switch. The tonguesB2, B4, and B1 are-connected respectively with segments 2, 4, and

1 in the distributor ring RI. The tongue 4 in the tape transmitter IIlis connected to the back contact associated with tongue B4 of thebell-signal keying switch.

The tongues 8 in positions I, 3, and 8 are unrelated to the keyingoperations for idle-time and bell-signal keying and, therefore, thesetongues are connected directly to appropriate segments I, 3, andi in thedistributor ring RI.

Whenever the transmission of trailic signals is to be interrupted forany appreciable time, it is desirable to maintain a succession ofidletime signals on a radio channel in order to hold the apparatus unitsat the receiving end in synchronism with the transmitting distributor.It is usual, therefore, to close a key switch consisting of contacts 3land 32 and having a toggle lever 29 which is manually operated. Theclosing of contacts 3l and 32 causes a negative potential to be fed fromcontact 32 through the coil of relay I6 and thence through a resistor 33to the positive terminal of an operating source, not shown.

When relay I6 operates, its tongues A2, A5, and A1 are closed againstfront contacts which are supplied with positive potential and thiscauses positive marking signals to be applied to segments 2, 5, and 1 inthe distributor ring RI. Bearing in mind that these segments arecyclically swept by the brush I8,-it will be seen that the idle-timesignal goes out over the transmission channel each time the ring RI istraversed. and until the toggle switch lever 29 is restored to normal.Incidentally, the switch lever '8 may be used to lock up the tapetransmitter in a manner described by James A. Spencer in his Patent No.2,160,463, granted May 30, 1939.

When the transmission of traffic signals is resumed, the perforated tapeis fed at a cyclic rate through the transmitter in accordance with thestep-by-step feeding thereof as indicated by the use of ratchet wheeland associated driving mechanism under control of the operating magnet34. This magnet is energized by the closing of a circuit through the twocoils of a differential relay 40 which, when both are energlzed,provides no attraction upon the relay armature 48. However, theenergizing impulse for magnet 34 is derived from positive potentialsthrough ring R4 and certain segments in ring R2 when they are bridged bythe brush 20. This operation takes place at the completion of sensingoperations at each step of the tape control device.

The relay 40 is designed to operate when one only of its windings isenergized, but will not operate when both windings are energized.Normally, then, the local pulses which are derived from segments 8, 9,and I0 in distributor ring R2 will be branched so that both windings ofrelay 40 will be simultaneously and equally energized. The branch forthe left hand winding of relay 4I) may be traced from conductor 36through conductor 42 to contact 43 and a companion contact 44 and thenceover conductor 45 to mutually engaging contacts 46 and 41 to the lefthand relay winding 40. 'I'he circuit just now traced may be opened uponthe occurrence of either of two conditions. Under one of theseconditions, the tape slack between the perforator (not shown) and thesprocket wheel on the shaft of the ratchet wheel 35' of the transmittermay be reduced to the point where contacts 48 and 41 are opened. Onlythe right `hand winding of relay 40 will remain energized and hence thisrelay will pull up its armature 48 for engagement with contact spring38. The spring combination 31, 38, and 48 is of the make-before-breaktype. Consequently, the operating magnet 34, instead of being fed withpositive impulses from ring R2 in the distributor, will now be fed bycontact may be made between springs 4l and 41 for neutralizing themagnetization in relay 4l. Upon release of the armature 46, normaltransmitting conditions will be restored provided the idle-time controlkey 29 has not been actuated.

The auxiliary signaling device particularly for transmission of bellsignals is herein shown'as a modification of certain apparatus which wasparticularly illustrated and described in Patent No. 1,275,559, grantedAugust 13,- 1918, to W. A. Houghtaling. In the Houghtaling device it wasnecessary to transmit case shift signals before and'after the bellsounding signal. According to my invention, the necessity fortransmitting case shift signals is eliminated.

The need for transmitting bell signals inde-l pendently of any signalswhich have been perforated in the tape' will be apparent to thoseskilled in the art. Such need arises commonly when there is anydiillculty in reception and a part of the message must be repeated.However, there are a number of signals which can be made by means ofdierent numbers of bell strokes. Accordingly, the extent of movement ofthe dialing member 50 may be determined by placing ones finger in anyone of the holes 5| and drawing the member towards oneself until thefinger strikes a stationary point 52. This operation is similar todialing a number on a conventional telephone set.

When the operator withdraws his nger from the selected hole 5| andreleases the dialing member 50 to be restored to its normal positionunder the influence of a coiled spring 60, this spring upon unwindingdrives the shaft 51 which carries a ratchet wheel 58 fixedly mountedthereon. A gear 56 is mounted on the shaft 51 and has projectingtherefrom a pivot pin for supporting a pawl 6|, this pawl being adaptedto engage with teeth of the ratchet wheel 58. The dialing member 50 anda switch controlling dog 59 are also xedly mounted on the shaft 51.During a dialing operation, the pawl 6| ratchets over the teeth of theratchet wheel 58, but during the return motion of the shaft 51, the pawl6| engages with a tooth of the ratchet wheel and causes the latter torotate backward, with shaft 51 carrying its gear 56 so asto impartrotation to the pinion 54 fixedly mounted on a shaft 53.

This shaft 53 also carries a code impulsing cam C| and a ratchet wheel55, both ilxedly mounted thereon.

The cam shaft 53 can rotate only as permitted by the operation of anescapement whose arms 63a are integral with an armature 63 which isunder control of a pulsating magnet 62. The impulses for actuating themagnet 62 are derived from the source fed through distributor ring R4,and across brush to segments 8, 9. and v||| of ring R2. This circuit maybe further traced through conductors 36 and 42 to contact springs 43 and69 and thence to the winding of magnet 62 and finally returning to thenegative side of the source. y

The circuit just described is one which is formed`upon manipulating thedial member 50,

due tothe fact that the dog 66 has been thereby withdrawn from pressureagainst the resilient contact spring 43. The tension in this springurges it, when released, away from contact with spring 44 and in contactwith spring 68 which is in circuit with the winding of magnet 62. Theoperating impulses from the distributor ring R2 are,therefore,"\transferred from the operating magnet 34 of the transmitterto the escapement magnet 62 of the auxiliary signaling device.

Depending upon the hole 5| which is fingered, from one to ve strokes ofthe bell will be produced at the receiver.

Upon each revolution ofthe brush 20, a single impulse will betransmitted to the escapement magnet 62. Consequently, successivesignals composed of marking elements in positions 2, 4,

f and 1 of the seven-unit code will be transmitted over segments 2, 4,and 1 on ring RI.

When the idler roller 25 rides over a hump in the cam CI, it restoresthe switch tongues B2, B4, and B1 to their back contacts. Only when theroller 25 rides into a depression in cam C| will the marking impulses beapplied to segments 2, 4, and 1 of the distributor ring for transmissionof the bell signal. This signal has been selected as one which is notused for character selection in traflic signaling. A differentcombination may, however, be substituted, since in the seven-unit code,there are 35 possible code combinations, whereas in the five-unit codeonly 32 kcombinations are available.

The gear ratio is made such that the cam C| will move the follower arm24 through a complete operating cycle corresponding to each position ofthe holes 5| in the operating segment 50. Furthermore, the bell signalis transmitted upon every other passage of the brush 20 `over segments8, 9, and l0, so long as the lever arm 59 is off normal and permitscontact to be made between springs 43 and 69. The ratchet wheel 55 has20 teeth and will rotate the cam C| one half revolution when ve of thebell signals are to be transmitted in succession. The resting positionof the ratchet wheel 55 is always one which will restore the switchtongues BI, B2, B4, and B1 to normal. The purpose of switch tongue BIand its associated front contact is to short-circuit the winding of theidle-time relay I6 whenever the bell signal is to be transmitted. Thus,the idle-time relay is automatically rendered ineffective whenever thebell-signal keying device is actuated.

It will be seen from the above that upon actuating the bell-signalkeying device, the tongues B2, B4, and B1 are moved to place markingpotential on their associated segments of the transmitting distributorring Rl and this operation is repeated in accordance with the dialfingering for producing the desired number of strokes of the bell at thereceiving station.

The receivingapparatus .The receiving apparatus, as arranged forreception of the bell signal, comprises signal distributor rings R5 andR1 and local distributor rings R6 and R8. Ring R1 has applied theretothe marking and spacing impulses of the received code combinations.Under conditions of trafilc signal reception, these code impulses aredistributed through the segments to 'l inclusive on distributor ring R5and thence to selected ones of a set of printer selector magnets P|P1.It will be understood that the signals as received over a wire line orradio channel are caused to actuate a keying relay R9. This relay hasitstongue connected to a receiving ring R1 and its associated contactskconnected to direct current source terminals of opposite polarity.

In parallel with the selector coils in positions 2, 4, and 1 are relays12, 14, and 11. As the marking impulses forA the bell signal combinationare received in sequence, these relays will be energized. Each relayperforms two circuit operations. One is to close a locking circuit forthe relays own winding, as by means of the contacts 1i. The other is toclose a selective circuit which is only completed when all three of therelays 12, 14, and 11 are actuated. Such a selective circuit includescontacts 13, 15, and 18. In this selective circuit are the sourceterminals and a magnet 19, the armature lll of which is extended into aclapper for the bell 8| Upon reception of any code signal other than thebell signal, even though one or two of the relays 12, 14, and 11 may beenergized, nevertheless, the failure to actuate all three of theserelays would result in the bell ringing circuit being kept open.Consequently, the bell is sounded only upon reception of the codeelements applied to segments 2, 4, and 1 in the distributor ring R5.

After reception of each bell signal, the brush traversing thedistributor rings R6 and RB will pass over segment 8, thereby causing an8th-pulse relay 82 to be energized. This relay has contacts 83 which areassociated with the printer mechanism and which need not be hereinconsidered. The relay 82 also has circuit-breaking contacts 84 which liein the return circuit between the positive source terminal and thelocking contacts 1| in relays 12, 14, and 11. Hence, by thisarrangement, relays 12, 14, and 11 become deenergized when thedistributor brush passes over segment 8 in ring R6.

It requires the repeated selection of relays 12, 14, and 11 incombination and in accordance with the bell ringing code signal forobtaining repeated strokes of the bell.

In the actuating circuits for each relay 12, 14, and 11, I preferablyuse resistors 85 for dissipating the energy in the residual fields ofthese relays.

The various advantages of the combined arrangement of transmitter codesignaling device, idle-time signaling device, and auxiliary signalingdevice will be apparent to those skilled in the art. The particularadvantage which is obtained by the use of my invention as compared withthe prior art lies in the simplified and more rapid procedure fortransmission of bell signals without the use of case shift signals. Thisadvantage is also accompanied by the avoidance of difficulties due toimproper printing of traffic signal characters in the upper case whenthey should be in the lower case, or vice-versa. This advantage will beparticularly noted when it is understood that the actuation of thebell-signal keying device does not involve case shifting. Even thoughtralc signals in the upper case may have been interrupted by the use ofthe bell code signal, nevertheless, upon restoration of trafilcsignaling, the upper case characters will continue to be printed.

By reference to Patent No. 2,183,147, issued December l2, 1939, to J. B.Moore et al., it will be noted that the seven-unit signaling code oftheir invention is so designed as to permit of automatic errorindication wheneverthe signal, as received, is composed of more or lessthan a xed number of marking elements, usually three. So the bellsignal,as transmitted by the apparatus of my invention is preferably composedof 'three marking elements and four spacing elements. It thus conformsto other code combinations in this respect.

In certain well-known types of telegraph printers, means are providedfor preventing the operation of the tape feed mechanism during receptionof signals for shift," and unshift, blank, etc. Such means are usuallyassociated with dummy pullbars which are actuated by the main operatingbail. These dummy pull-bars are selected in response to the reception oftheir ap'- propriate signals and cooperate with a so-called fspacingcut-out universal bar for preventing the operation of the space lever.Hence, the tape is not fed forward when "stunt signals are received. Inlike manner a dummy pull-bar is preferably provided for selection by thebell signal, and this pull-bar serves to prevent the feeding of the tapewhen sounding the bell signal. A further function of the dummy pull-barin certain types of printers is to prevent the operation of anerror-indicating device. I have not, however, illustrated mechanism fortape fee-:l and mis-selection indicator prevention, since it forms nopart of my invention.

Whenever the bell signal becomes mutilated, the receiving printer iscaused to print an error symbol as a substitute for'ringing the bell, aswill be understood from the fact that the function of theerror-indicating device is conventionally performed in response to anydeparture of the received signals from their normal make- 11p.

Various modifications of my invention will doubtless suggest themselvesto those skilled in the art in view of the foregoing description. I donot intend, therefore, to be limited to the particular arrangement ofpartsas herein disclosed for practicing the invention.

I claim:

1. A signaling device comprising a tape-controlled character-code keyer,an idle-time signal keyer, and a bell-signal keyer, each of said key"-ers having switching means whereby the marking elements of diierent codesignals are composed, a transmitter having distributor means forcollecting successively different elemental pulses of marking andspacing significance fed thereto in accordance with the operation ofsaid keyers, manipulative means for causing said bell-signal keyer totransmit a bell-signal representing a selected number of bell strokes,the signal for each stroke being confined t0 one operating cycle of saiddistributor means, and said distributor means being arranged and adaptedto complete only one cycle between any two successive bell strokesignals, a receiver for responding to signals initiated by any of saidkeyers, a plurality of relays individually responsive to differentmarking elements of a bell-signal, and means including anelectromagnetic device, operable upon closing a circult thereforethrough all of said relays, whereby said selected number of bell strokesis produced.

2. A signaling device according to claim l and including means forcausing the character code keyer to be disabled by the idle-time keyer,and means for causing both the character-code keyer and the idle-timekeyer to be disabled by the bell-signal keyer,

3. In a typewriting telegraph system, the method of transmittingintelligence and of con- Y panied by case-shift signals, and means forcaustrolling a bell having an electromagnetically operable clapper,which comprises transmitting coded intelligence signals the response towhich depends upon the transmission of a precedent case-shift signal,transmitting coded bell signals the response to which is independent 0fprecedent case-shift signals, and causing the clapper of said bell torespond to the reception of an uninterrupted succession of said bellsignals by making a number of clapper strokes equal to the number ofvreceived bell signals.

4. Signal transmitting apparatus adapted for use in a synchronousprinting telegraph system, comprising a line, a perforatedtape-controlled transmitter including means for composing the elementsof character signals and case-shift signals. an idle-time keyer, a`bell-signal keyer, cyclically operable means for impressing signals uponsaid line when codified by said transmitter for message transmission andat other times by a selected one of said keyers, said signals whencodied by the transmitter being of duel significance in that they relateto upper and lower case printing characters, and said signals whencodified by said keyers being independent of upper and lower casedesignation, -means enabling said keyers to transmit their signalsunaccoming said transmitter and said keyers each to impress signals uponthe line at mutually exclusive periods.

5. Apparatus according to c laim 4 and including means for assigning afixed number of marking elements to each of the signals whether codiedby said transmitter or by either of said keyers.

6. Signal receiving apparatus comprising a printing telegraph instrumentoperable in response to code signals having a uniform number of markingelements and a uniform number of spacing elements, means in saidinstrument for causing it to respond in one way to character signalswhich follow the reception of a gure shift" signal, and to respond in adifferent way to character signals which follow the reception of aletter shift signal, a. bell Stroker, a relay system responsive to thereception of a bell signal combination of marking and spacing elements,said bell signal being of unalterable significance and independent ofthe transmission of said figure shift` and letter shift" signals, and anoperating circuit closeable by said relay system for actuating said bellstroker.

ANDREW L./BROWN.

